1. Field of the Invention
This invention relates to a method of manufacturing a porous polytetrafluoroethylene (PTFE) tube. The tube may optionally contain a filler.
2. Description of the Prior Art
A porous PTFE tube is usually manufactured by a method which comprises extruding a tubular PTFE product, stretching it longitudinally into a tube several times its original length to make it porous, heating the tube to a temperature higher than the melting point of PTFE, while it is held in its stretched length. Such a tube which has high longitudinal strength can be produced by the method described in U.S. Pat. No. 3,953,566. The ability of this tube to resist internal pressure is, in certain cases, unsatisfactory. It is difficult to manufacture a porous PTFE tube having a thin wall or a small diameter by this method.